Image forming system and image forming apparatus

ABSTRACT

An image forming system according to the present invention includes a jam detection unit  111  which detects a jam of a paper conveyed along conveyance paths  118   e,    127, 138 , and  148  of an image forming system  100 , and a control unit  111  which temporarily stops the conveyance of papers when the jam has been detected by the jam detection unit, after the originating paper is removed, conveys papers, other than an originating paper having caused the jam, remaining in the conveyance path in such away that an interval between a preceding paper and a following paper in the conveyance path is expanded, and discharges the papers from the image forming system.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2014-104689 filed on May 20, 2014, the contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an image forming system and an image forming apparatus.

2. Description of Related Art

In the image forming system, when a jam such as a paper jam occurs in a paper conveyance path, automatic purge which is automatic discharge of papers remaining in the conveyance path after conveyance of papers is stopped and an originating paper of the jam is removed, is performed. The automatic purge is performed, so that it is possible to reduce a load for the jam processing by a user such as removal work of remaining papers.

However, with the high functionality of the image forming system and the complication of the conveyance path, at the time of conveyance of papers by the automatic purge, it is highly probable that the jam occurs again. When the jam occurs again at the time of the automatic purge, the following problems occur. That is, (1) It is difficult to perform a pre-purge process of discharging papers remaining in the conveyance path until the conveyance of papers is stopped after the jam occurs again, or to avoid the stay of papers after the transfer or fixing of an image in order to perform the automatic purge again. (2) When a paper interval is narrower than that at the time of normal paper conveyance due to the reoccurrence of the jam, since the originating paper having caused the jam and a following paper collide with each other until the conveyance of papers is stopped, it is highly probable that jam processability deteriorates as compared with a case in which normal jam has occurred. Furthermore, since a part of the papers stay in a paper feeding cassette when the conveyance of papers has been stopped, it is highly probable that it is not possible to perform anti-guillotine control for preventing the paper feeding cassette from serving as guillotine to tear a recording paper. (3) Ordinarily, in the automatic purge which is performed in order to reduce the load of the user for jam processing, the jam occurs again, resulting in an increase in a downtime of the system and deterioration of the reliability of the user for the system.

As a technology for preventing the jam from occurring again at the time of the automatic purge, there is the technology disclosed in Unexamined Japanese Patent Publication No. 2000-95389. That is, at the time of the automatic purge, each conveyance driving motor which is corresponding to each of at least two or more paper conveyance paths having a merging point is controlled to sequentially start the conveyance of remaining papers at a proper time difference so that papers remaining in each paper conveyance path do not collide with each other at the merging point. In this way, the collision of the papers at the merging point is prevented, so that the jam is prevented from occurring again.

SUMMARY

However, in the automatic purge, even though the collision of the papers at the merging point of the conveyance path is prevented, since it is probable that the jam occurs again at places other than the merging point due to the following factors, the conventional technology has a problem that it is not possible to prevent such jam from occurring again.

(1) Depending on the positions of the remaining papers when conveyance has been stopped by the occurrence of the jam, at the time of automatic purge, differently from the normal case in which papers are fed from a tray, there is a case in which the remaining papers do not pass through a conveyance path in which pre-resist for correcting the inclination of the paper once after paper feeding or resist for correcting the inclination of the paper before the transfer of the image is performed. In this way, in the case in which papers are inclined when the conveyance has been stopped by the occurrence of the jam, the correction thereof is not possible or is not sufficient.

(2) When papers remain in a transfer unit or a fixing unit, since the damage of the papers becomes large and thus the reconveyance of the papers is not possible, there is a case in which the remaining papers are withdrawn to ADU (Auto Duplex Unit) in order to prevent the remaining papers from remaining in the transfer unit or the fixing unit. In this way, a paper interval of the withdrawn remaining papers becomes narrower than a reference interval which is the paper interval provided in normal paper conveyance.

(3) In the conveyance path of an image forming apparatus, stop points for waiting for the conveyance of preceding papers are provided at a plurality of places in the normal paper conveyance. However, when the conveyance is stopped by the occurrence of the jam, there is a case in which remaining papers are stopped at places other than the stop points. When the remaining papers are reconveyed from those places other than the stop points, it is not possible to normally convey the remaining papers or it is probable that bending or inclination occurs in the remaining papers.

(4) After the occurrence of the jam, when it takes a time to start the automatic purge, if remaining papers remain in the conveyance path with a large curvature, the remaining papers are curled, thereby probably affecting conveyance.

The present invention has been made to solve the problems described above. That is, an object of the present invention is to prevent or reduce the reoccurrence of the jam in the automatic purge or to prevent jam processability from deteriorating regardless of the places of remaining papers when conveyance has been stopped by the occurrence of the jam.

To achieve at least one of the abovementioned objects, an image forming system reflecting one aspect of the present invention includes the followings.

(1) An image forming system comprising: a jam detection unit which detects a jam of a paper conveyed along a conveyance path of said image forming system; and a control unit which temporarily stops conveyance of the paper when said jam detection unit has detected said jam, after an originating paper having caused said jam is removed, conveys papers, other than said originating paper, remaining in said conveyance path in such a way that an interval between a preceding paper and a following paper in said conveyance path is expanded, and discharges said papers from said image forming system.

(2) The image forming system as described in above (1), wherein, before temporarily stopping said conveyance of said paper after said jam detection unit detects said jam, said control unit withdraws said papers, other than said originating paper, by conveying said papers to a place other than a predetermined specific place in said conveyance path.

(3) The image forming system as described in above (1), wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying start of conveyance of said following paper by a predetermined time from start of conveyance of said preceding paper.

(4) The image forming system as described in above (1), wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded to be equal to or more than a reference interval provided in normal paper conveyance.

(5) The image forming system as described in above (3), wherein, when said preceding paper remains in a temporary stop position of a paper set in normal paper conveyance, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is maintained or expanded by simultaneously performing said start of said conveyance of said following paper and said start of said conveyance of said preceding paper or delaying said start of said conveyance of said following paper by a first time as said predetermined time from said start of said conveyance of said preceding paper, and when said preceding paper remains in a position other than said temporary stop position, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a second time as said predetermined time longer than said first time from said start of said conveyance of said preceding paper.

(6) The image forming system as described in above (3), further comprising: a correction unit which corrects at least one of bending, inclination, and deviation of the passing paper, wherein, when said correction unit exists in said conveyance path from a remaining position of said preceding paper to discharge positions of the papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said conveyance of said following paper and said conveyance of said preceding paper are simultaneously started, and when said correction unit does not exist in said conveyance path from said remaining position of said preceding paper to said discharge positions of said papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a third time as the predetermined time from said start of said conveyance of said preceding paper.

(7) The image forming system as described in above (4), wherein, when the interval between the remaining position of said preceding paper and the remaining position of said following paper in said conveyance path is narrower than said reference interval, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a fourth time as the predetermined time from said start of said conveyance of said preceding paper, and when said interval between said remaining position of said preceding paper and said remaining position of said following paper is equal to or wider than said reference interval, said control unit simultaneously starts said conveyance of said following paper and said conveyance of said preceding paper.

(8) The image forming system as described in above (1), further comprising: a first detection unit which detects a paper, which exists in at least a position of said conveyance path conveyed by each conveyance driving source, in said each conveyance driving source respectively, wherein, when said first detection unit detects that said preceding paper and said following paper remain in at least positions of said conveyance path conveyed by a common first conveyance driving source, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by conveying said preceding paper and said following paper until said preceding paper passes through at least said position of said conveyance path conveyed by said first conveyance driving source, temporarily stopping conveyance of said following paper by said first conveyance driving source and conveying said preceding paper by a second conveyance driving source other than said first conveyance driving source when said preceding paper has passed through at least said position of said conveyance path conveyed by said first conveyance driving source, and restarting said conveyance of said following paper by said first conveyance driving source after a predetermined fifth time passes, and discharges said papers from said image forming system.

(9) The image forming system as described in above (1), further comprising: a second detection unit which detects that a paper has passed through a predetermined position in said conveyance path, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by starting conveyance of said following paper when said second detection unit detects that said preceding paper has passed through said predetermined position of said conveyance path after conveyance of said preceding paper is started.

The objects, features, and characteristics of this invention other than those set forth above will become apparent from the description given herein below with reference to preferred embodiments illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image forming system according to a first embodiment of the present invention;

FIG. 2 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention;

FIG. 3 is a block diagram illustrating a configuration of a humidifying device;

FIG. 4 is a block diagram illustrating a configuration of a post-processing device;

FIG. 5 is a block diagram illustrating a configuration of a paper feeding device;

FIG. 6 is an entire configuration diagram of the image forming system according to a second embodiment of the present invention;

FIG. 7 is an explanation diagram illustrating places of papers remaining in the image forming system when the jam has occurred in the post-processing device;

FIG. 8 is an explanation diagram illustrating places of papers withdrawn to ADU before the conveyance of the papers is temporarily stopped after the occurrence of the jam;

FIG. 9 is an explanation diagram illustrating places of withdrawn papers together with a discharge order of each paper from the image forming apparatus in automatic purge;

FIG. 10 is an explanation diagram illustrating places of the papers remaining in the humidifying device of the image forming system when the jam has occurred in the post-processing device;

FIG. 11 is an explanation diagram illustrating places of the papers withdrawn to places, other than specific places, in the humidifying device before paper conveyance is temporarily stopped after the occurrence of the jam;

FIG. 12 is a flowchart illustrating processing from the jam occurrence to the automatic purge by the image forming system;

FIG. 13 is a sub-routine flowchart of step S125 of the flowchart of FIG. 12;

FIG. 14 is a diagram illustrating a detailed flow of determination in step S135 of the sub-routine flowchart of FIG. 13;

FIG. 15 is an explanation diagram illustrating places of the remaining papers in the state in which the papers have been withdrawn to places other than specific places in the humidifying device before paper conveyance is temporarily stopped after the occurrence of the jam;

FIG. 16 is an explanation diagram illustrating the state in which the automatic purge is performed from the state of FIG. 15 and a preceding paper has passed through the position of the conveyance path conveyed by a common conveyance driving source together with a following paper;

FIG. 17 is a flowchart of the automatic purge in the second embodiment of the present invention and is the sub-routine flowchart of step S125 of the flowchart of FIG. 12; and

FIG. 18 is a flowchart of the automatic purge in a third embodiment of the present invention and is the sub-routine flowchart of step S125 of the flowchart of FIG. 12.

DETAILED DESCRIPTION

Hereinafter, an image forming system and an image forming apparatus according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a block diagram of the image forming system according to a first embodiment of the present invention.

As illustrated in FIG. 1, the image forming system 100 includes the image forming apparatus 110, a paper feeding device 120, a humidifying device 130, and a post-processing device 140. The paper feeding device 120, the humidifying device 130, and the post-processing device 140 are devices provided according to necessity, and the image forming system 100 may not have these devices.

The image forming apparatus 110, the paper feeding device 120, the humidifying device 130, and the post-processing device 140 are communicably connected to one another via a network 150. The network 150 can be configured by a LAN (Local Area Network) connecting computers or network devices to one another based on a standard such as the Ethernet (a registered trademark) and FDDI (Fiber-Distributed Data Interface).

FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus.

As illustrated in FIG. 2, the image forming apparatus 110 includes a CPU (Central Processing Unit) 111, a storage unit 112, a communication interface 113, an operation unit 114, a display unit 115, an image control unit 116, a reading unit 117, an engine 118, and a paper sensor 1119. These elements are connected to one another via a bus 119 for exchanging signals.

The storage unit 112 can be configured by RAM (Random Access Memory), ROM (Read Only Memory), and HDD (Hard Disk Drive). The RAM temporarily stores a program executed by the CPU 111 or data processed by the CPU 111. The ROM stores various programs or various kinds of data. The HDD stores various programs including a program for controlling each element of the image forming apparatus 110 by the CPU 111, image data received through the communication interface 113 or the reading unit 117, and other various kinds of data.

The communication interface 113 is an interface for performing communication between the image forming apparatus 110 and an external device, and a network interface based on a standard such as the Ethernet (a registered trademark), SATA, PCI, Express, USB, and IEEE 1394, various local connection interfaces such as a wireless communication interface such as the Bluetooth (a registered trademark) and IEEE 802.11, or the like, are used.

The operation unit 114 includes touch panel for performing various types of setting, various fixed keys or the like such as a numeric keypad for setting the number of copies or the like, a start key for instructing the start of an operation, a stop key for instructing the stop of an operation, and a reset key for initializing various setting conditions.

The display unit 115 includes a touch panel for displaying various types of information and inputting various types of setting, various fixed keys such as a numeric keypad for setting the number of copies or the like, a start key for instructing the start of an operation, a stop key for instructing the stop of an operation, and a reset key for initializing various setting conditions, and a display lamp or the like. Overlapping functions of the operation unit 114 and the display unit 115 may be included in any one of the operation unit 114 and the display unit 115.

The image control unit 116 performs a layout process and a rasterization process of print data included in a print job received by the communication interface 113, and generates image data which is data of a bitmap type image. The print job is a generic term of a print command for the image forming apparatus 110 and includes print data and print setting. The print data is data of a document to be printed, and for example, may include various kinds of data such as image data, vector data, and text data. In detail, the print data may be PDL (Page Description Language) data, PDF (Portable Document Format) data, or TIFF (Tagged Image File Format) data. The print setting is setting regarding image formation to a paper and post-processing of a printed matter, and for example, may include various types of setting such as a paper type, a grayscale or a full color, 2in1, duplex printing, stapling, punching, and folding.

The reading unit 117 irradiates a document, which has been set in a predetermined reading position of a document platen, by using a light source such as a fluorescent lamp, photoelectrically converts reflected light into an electrical signal by using an imaging device such as a CCD (Charge Coupled Device) image sensor, and generates image data from the electrical signal.

The engine 118 performs image formation based on the image data on the paper through each process of charging, exposure, development, transfer, and fixing by an electrophotographic scheme, and then outputs the paper.

The paper sensor 119 detects positions of the papers in a conveyance path. The paper sensor 119, for example, can be configured by a line sensor provided at a required place of the conveyance path.

The CPU 111 constitutes a control unit, and constitutes a jam detection unit together with the paper sensor 119.

The CPU 111 performs the control of the aforementioned each element, various arithmetic processes or the like according to the program. More specifically, the CPU 111 performs general control regarding various processes, image formation, and storing while cooperating with each element constituting the image forming apparatus 110.

The CPU 111 detects the jam having occurred in the image forming apparatus 110 on the basis of the positions of the papers in the conveyance path detected by the paper sensor 1119. For example, the CPU 111 can detect the jam by no change in the positions of the papers even though control for conveying the papers is performed.

The CPU 111 communicates with the humidifying device 130, the post-processing device 140, and the paper feeding device 120, which are devices (hereinafter, referred to as “other devices”) except for the image forming apparatus 110 of the image forming system 100, and receives information on the occurrence of the jam having occurred in the other devices from the other devices. When the jam has occurred in the image forming system 100 or the other devices, the CPU 111 temporarily stops the conveyance of papers, and transmits information on the occurrence of the jam to the other devices so as to temporarily stop the conveyance of the papers in the other devices. At this time, the positions, the number or the like of the papers temporarily stopped in the other devices are received by the CPU 111 from the other devices.

After an originating paper having caused the jam is removed by a user, the CPU 111 conveys respective papers, other than the originating paper, remaining in the conveyance path in such away that an interval between a preceding paper and a following paper in the conveyance path is expanded, and discharges the papers from the image forming apparatus by an automatic purge. In this way, it is possible to prevent or reduce the reoccurrence of the jam due to a collision of the preceding paper and the following paper in the automatic purge.

FIG. 3 is a block diagram illustrating a configuration of the humidifying device.

As illustrated in FIG. 3, the humidifying device 130 includes a CPU 131, a storage unit 132, a communication interface 133, a paper feeding unit 134, a paper discharge unit 135, a humidifying unit 136, and a paper sensor 139. These elements are connected to one another via a bus 137 for exchanging signals.

The storage unit 132 stores a program for controlling each element of the humidifying device 130 by the CPU 131, and various kinds of data such as paper information received through the communication interface 133. The storage unit 132, for example, can be configured by RAM and HDD.

The communication interface 133 is an interface for performing communication between the humidifying device 130 and the image forming apparatus 110/the post-processing device 140, and the Ethernet or the like is used.

To the paper feeding unit 134, the papers for which image formation has been performed are input by the image forming apparatus 110.

The paper discharge unit 135 outputs papers humidified by the humidifying unit 136.

The humidifying unit 136 humidifies the paper passing therethrough by uniformly supplying water to both surfaces of the paper. In this way, the water content of the paper increases, so that it is possible to reduce the waviness of the paper.

The paper sensor 139 detects positions of the papers in the conveyance path. The paper sensor 139, for example, can be configured by a line sensor provided at a required place of the conveyance path.

The CPU 131 constitutes a control unit, and constitutes a jam detection unit together with the paper sensor 139.

The CPU 131 performs the control of the aforementioned each element, various arithmetic processes or the like according to the program. More specifically, the CPU 131 performs general control regarding paper humidification while cooperating with each element constituting the humidifying device 130.

The CPU 131 detects the jam having occurred in the humidifying device 130 based on the positions of the papers in the conveyance path detected by the paper sensor 139. For example, the CPU 131 can detect the jam by no change in the positions of the papers even though control for conveying the papers is performed. The CPU 131 transmits information on the occurrence of the jam in the humidifying device 130 to the image forming apparatus 110 by the communication interface 133.

FIG. 4 is a block diagram illustrating a configuration of the post-processing device.

As illustrated in FIG. 4, the post-processing device 140 includes a CPU 141, a storage unit 142, a communication interface 143, a paper feeding unit 144, an output unit 145, a stitching unit 146, and a paper sensor 149. These elements are connected to one another via a bus 147 for exchanging signals.

The storage unit 142 stores a program for controlling each element of the post-processing device 140 by the CPU 141, and various kinds of data such as the print setting received through the communication interface 143. The storage unit 142, for example, can be configured by RAM and HDD.

The communication interface 143 is an interface for performing communication between the post-processing device 140 and the image forming apparatus 110/the paper humidifying device 130, and the Ethernet or the like is used.

To the paper feeding unit 144, the papers for which the waviness of papers has been reduced by the humidifying device 130 are input.

The output unit 145 outputs the papers subjected to post-processing as the printed matters.

The stitching unit 146 performs side stitching on the papers.

The paper sensor 149 detects positions of the papers in the conveyance path. The paper sensor 149, for example, can be configured by the line sensor provided at the required place of the conveyance path.

The CPU 141 constitutes a control unit, and constitutes a jam detection unit together with the paper sensor 149.

The CPU 141 performs the control of the aforementioned each element, various arithmetic processes or the like according to the program. On the basis of the print setting of the print job, the CPU 141 controls the stitching unit 146 to perform side stitching which is post-processing of the paper.

The CPU 141 detects the jam having occurred in the post-processing device 140 based on the positions of the papers in the conveyance path detected by the paper sensor 149. For example, the CPU 141 can detect the jam by no change in the positions of the papers even though control for conveying the papers is performed. The CPU 141 transmits information on the occurrence of the jam in the post-processing device 140 to the image forming apparatus 110 by the communication interface 143.

FIG. 5 is a block diagram illustrating a configuration of the paper feeding device.

As illustrated in FIG. 5, the paper feeding device 120 includes a CPU 121, a storage unit 122, a communication interface 123, a paper feeding unit 124, and a paper sensor 128. These elements are connected to one another via a bus 126 for exchanging signals.

The storage unit 122 stores a program for controlling each element of the paper feeding device 120 by the CPU 121, and various kinds of data. The storage unit 122, for example, can be configured by RAM and HDD.

The communication interface 123 is an interface for performing communication between the paper feeding device 120 and the image forming apparatus 110, and the Ethernet or the like is used.

The paper feeding unit 124 has a plurality of paper feeding trays and paper feeding rollers, conveys the papers taken out from each paper feeding tray by the paper feeding rollers, and supplies the image forming apparatus 110 with the taken-out papers.

The paper sensor 128 detects positions of the papers in the conveyance path. The paper sensor 128, for example, can be configured by the line sensor provided at the required place of the conveyance path.

The CPU 121 constitutes a control unit, and constitutes a jam detection unit together with the paper sensor 128.

The CPU 121 performs the control of the aforementioned each element, various arithmetic processes or the like according to the program. The CPU 121 controls the paper feeding unit 124 so as to feed papers from each paper feeding tray of the paper feeding unit 124 to the image forming apparatus 110.

The CPU 121 detects the jam having occurred in the paper feeding device 120 based on the positions of the papers in the conveyance path detected by the paper sensor 128. For example, the CPU 121 can detect the jam by no change in the positions of the papers even though control for conveying the papers is performed. The CPU 121 transmits information on the occurrence of the jam in the paper feeding device 120 to the image forming apparatus 110 by the communication interface 123.

FIG. 6 is an entire configuration diagram of the image forming system according to the present embodiment.

As described above, the image forming system 100 includes the image forming apparatus 110, the paper feeding device 120, the humidifying device 130, and the post-processing device 140, and is configured by connecting these devices to one another. The papers pass through each device in sequence of the paper feeding device 120, the image forming apparatus 110, the humidifying device 130, and the post-processing device 140. More specifically, the papers fed from the paper feeding device 120 to the image forming apparatus 110 are subjected to image formation by the image forming apparatus 110, humidified by the humidifying device 130, and then subjected to post-processing by the post-processing device 140 for output.

The image forming apparatus 110 controls the conveyance of the papers in the conveyance path 118 e under the control of the CPU 111, and performs image formation on papers by a transfer unit 118 b and a fixing unit 118 c which are elements of the engine 118. Furthermore, the image forming apparatus 110 makes the paper pass through an ADU 1110 and reverses the front and the back of the paper in the conveyance path 118 e, thereby performing the image formation on both surfaces of the paper.

A resist roller 118 a constitutes a correction unit and corrects bending, inclination, and deviation of the paper conveyed along the conveyance path 118 e. The bending, the inclination, and the deviation of the paper in the conveyance path 118 e are corrected, so that it is possible to improve the accuracy of the position of the image formed on the paper and to suppress the occurrence of the jam due to paper conveyance failure.

The transfer unit 118 b, for example, includes a photosensitive drum. The surface of the photosensitive drum is uniformly charged by a charging unit (not illustrated), and irradiated with laser light by an optical writing unit (not illustrated) according to an image information signal so as to form a latent image. The latent image is developed by a developing unit (not illustrated), resulting in the formation of a toner image. The toner image is transferred to the paper whose inclination has been corrected by the resist roller 118 a, by the transfer unit 118 b in the conveyance path 118 e.

The fixing unit 118 c includes a heating roller and a pressing roller, and forms a nip area having an approximately arc shape formed when the heating roller is pressed by the pressing roller. The paper with the transferred toner image passes through the nip area of the fixing unit 118 c so that a side with the toner image placed thereon becomes convex, and toner of the toner image is pressed and heated, so that the toner image is fixed to the paper.

The ADU 1110 includes a first ADU conveyance path 1110 a, a second ADU conveyance path 1110 b, a third ADU conveyance path 1110 c, and ADU conveyance rollers 1111 provided in the respective ADU conveyance paths 1110 a, 1110 b, and 1110 c. The ADU 1110 conveys the paper, whose surface is subjected to the image formation and has been input to the first ADU conveyance path 1110 a, to the second ADU conveyance path 1110 b by the ADU conveyance roller 1111. In the second ADU conveyance path 1110 b, the surface of the paper faces a direction (that is, a vertical downward direction) in which the surface contacts with the second ADU conveyance path 1110 b. The ADU 1110 conveys the paper from the second ADU conveyance path 1110 b to the third ADU conveyance path 1110 c by the ADU conveyance roller 1111. In the third ADU conveyance path 1110 c, the surface of the paper faces a direction (that is, a vertical upward direction) in which the surface does not contact with the third ADU conveyance path 1110 c. Then, the ADU 1110 conveys the paper from the third ADU conveyance path 1110 c to an upstream of the resist roller 118 a of the conveyance path 118 e by the ADU conveyance roller 1111. In the conveyance path 118 e, since the surface of the paper faces a direction (that is, a vertical downward direction) in which the surface contacts with the conveyance path 118 e and the back surface of the paper faces a direction (that is, a vertical upward direction) in which the surface does not contact with the conveyance path 118 e, the front and the back of the paper are reversed in a direction in which image formation can be performed on the back surface. The inclination and the like of the paper are corrected again by the resist roller 118 a, and the image formation is performed on the back surface by the transfer unit 118 b and the fixing unit 118 c, so that the image formation is performed on the front and back of the paper.

The humidifying device 130 makes the paper pass through a humidifying roller of the humidifying unit 136 provided in the conveyance path 138 under the control of the CPU 131, and humidifies the paper, thereby reducing the waviness of the paper.

The post-processing device 140 performs the side stitching on the paper by the stitching unit 146 based on the print setting of the print job under the control of the control unit 141. The paper to be subjected to the side stitching is conveyed to the stitching unit 146 by the conveyance path 148 c among three conveyance paths 148 b, 148 c, and 148 d branched from a conveyance path 148 a, is subjected to the side stitching, and then is output to an output tray 145 c. The paper not to be subjected to the side stitching is conveyed by the conveyance path 148 b for output.

The paper feeding device 120 takes out the papers from any one of paper feeding trays 124 a, 124 b, and 124 c by a paper feeding roller (not illustrated) in response to a paper type required from the image forming apparatus 110, and feeds the papers to the image forming apparatus 110 through the conveyance path 127 under the control of the CPU 121.

The image forming apparatus 110 will be further described in detail.

The ADU 1110 is available as a withdrawing place for the withdrawal of papers, other than an originating paper of jam, to a place other than predetermined specific places in the conveyance path 118 e before the conveyance of papers are temporarily stopped due to the occurrence of the jam in the image forming system 100. The papers withdrawn to the ADU 1110 are discharged from the image forming apparatus 110 by automatic purge performed after the originating paper is removed by the user, and then are discharged to outside of the image forming system 100. The specific places are places at which paper conveyance failure may occur frequently when paper reconveyance is started from the specific place by the automatic purge, and can be set in advance in the image forming apparatus 110 by the user. For example, installation places of the transfer unit 118 b, the fixing unit 118 c, and the resist roller 118 a may be set as the specific places. The reason for setting the transfer unit 118 b as the specific place is because when a paper is temporarily stopped in the transfer unit 118 b and when the paper is retransmitted from the transfer unit 118 b, the paper may be broken or deformed by the photosensitive drum and paper conveyance failure may occur. The reason for setting the fixing unit 118 c as the specific place is because when the paper is temporarily stopped in the fixing unit 118 c and when the paper is retransmitted from the fixing unit 118 c, the paper may be broken or deformed by the heating roller and the pressing roller. Furthermore, this is because when the paper stayed in the fixing unit 118 c is continuously heated and pressed, the paper may be broken or deformed, and at the time of paper reconveyance, paper conveyance failure may occur. The reason for setting the resist roller 118 a as the specific place is because the paper may be broken or deformed by the resist roller 118 a when the paper is temporarily stopped in the place and when the paper is reconveyed from the place, and because correction for the inclination of the paper in the conveyance path 118 e may not be sufficient when paper reconveyance is started from the state in which the paper has been caught by the resist roller 118 a, and paper conveyance failure may occur when the paper is obliquely conveyed.

The specific place may be a place of the conveyance path with a relatively large curvature. This is because when the paper remains in the place of the conveyance path with a relatively large curvature, the paper may be curled and paper conveyance failure may occur.

FIG. 7 is an explanation diagram illustrating places of the papers remaining in the image forming system when the jam has occurred in the post-processing device. FIG. 8 is an explanation diagram illustrating places of the papers withdrawn to the ADU before the conveyance of papers is temporarily stopped after the occurrence of the jam. In FIG. 7 and FIG. 8, the humidifying device 130 is omitted in order to facilitate a description.

In FIG. 7, the occurrence place of the jam is indicated by a mark X, and the paper P1 serves as the originating paper at a branch point at which the three conveyance paths 148 b, 148 c, and 148 d are branched from the conveyance path 148 a of the post-processing device 140, resulting in the occurrence of the jam. The number of the papers, other than the originating paper, remaining in the image forming system 100 when the jam has occurred is 6, wherein four papers P2, P3, P4, and P5 remain in the conveyance path of the image forming apparatus 110, and two papers P6 and P7 remain in the conveyance path 127 of the paper feeding device 120.

In FIG. 8, among the papers P2 to P5 remaining in the image forming apparatus 110 at the time of the occurrence of the jam, the papers P2, P4, and P5 remaining in the installation places of the transfer unit 118 b, the fixing unit 118 c, and the resist roller 118 a, which are the specific places, are conveyed to the ADU 1110 for withdrawal. The paper P3 existing in the ADU 1110 at the time of the occurrence of the jam is also conveyed according to necessity in order to form a space among the papers P2 to P5 remaining in the ADU 1110.

Since the papers P6 and P7 remaining in the conveyance path 127 of the paper feeding device 120 do not remain in the specific places, they are not withdrawn. However, when the papers P6 and P7 remain in the specific places provided in the conveyance path 127 of the paper feeding device 120, these papers P6 and P7 are conveyed to places of the conveyance path 127, other than the specific places, and are withdrawn.

The conveyance for withdrawing the papers P2, P4, and P5 remaining in the specific places to the ADU 1110, for example, can be performed as follows. The paper P3 is conveyed to the resist roller 118 a and is stopped under the control of the resist roller 118 a, and the conveyance of the papers P4, P2, and P5 in the conveyance path 118 e is continued and they are input to the ADU 1110 in sequence of the paper P4, the paper P2, and the paper P5. Then, the paper P4, the paper P2, and the paper P5 are conveyed to the third ADU conveyance path 1110 c, the second ADU conveyance path 1110 b, and the first ADU conveyance path 1110 a respectively under the control of each ADU conveyance roller 1111 and are stopped.

As described above, the papers P2, P4, and P5 remaining in the specific places are withdrawn to the ADU 1110, which are places other than the specific places, and automatic purge is performed from the places other than the specific places, so that it is possible to suppress paper conveyance failure in the automatic purge.

FIG. 9 is an explanation diagram illustrating places of withdrawn papers together with a discharge order of each paper from the image forming apparatus in the automatic purge. FIG. 9 illustrates the state in which the papers are temporarily stopped in the state of withdrawn and the originating paper P1 has been removed by the user.

In FIG. 9, numbers written in parentheses of the papers P2 to P7 indicate a discharge order of each paper from the image forming apparatus 110.

Under the control of the CPU 141, the image forming apparatus 110 decides the discharge order of each paper from the image forming apparatus 110 based on the positions of the papers remaining in the image forming apparatus 110 which are detected by the paper sensor 119, and the positions of the papers remaining in the paper feeding device 120 which are detected by the paper sensor 128, and received from the paper feeding device 120. The discharge order is decided as an order of papers more quickly dischargeable from the image forming apparatus 110 by conveyance. In the automatic purge, the papers are discharged from the image forming apparatus 110 in the decided discharge order. Specifically, in the automatic purge, the papers are discharged from the image forming apparatus 110 in sequence of the paper P3, the paper P4, the paper P2, the paper P5, the paper P6, and the paper P7.

In the image forming apparatus 110, after the papers P2 to P5 are withdrawn and the originating paper P1 is removed by the user, the papers P2 to P7 remaining in the image forming apparatus 110 and the paper feeding device 120 are conveyed by the automatic purge in such a way that an interval of a preceding paper and a following paper in the conveyance path 118 e is expanded. Specifically, the papers P2 to P7 are conveyed such that an interval of the paper P3, which is the preceding paper in terms of a relation with the paper P4, and the paper P4 serving as the following paper is expanded. Similarly, the papers P2 to P7 are conveyed in such a way that an interval of the preceding paper P4 and the following paper P2, an interval of the preceding paper P2 and the following paper P5, an interval of the preceding paper P5 and the following paper P6, and an interval of the preceding paper P6 and the following paper P7 are expanded. In this way, a collision of the preceding paper and the following paper is suppressed, so that regardless of the positions of remaining papers when conveyance has been stopped due to the occurrence of jam, it is possible to prevent or reduce the reoccurrence of the jam in the automatic purge and to prevent jam processablity from deteriorating.

In the automatic purge, it is preferably to convey papers such that an interval of the preceding paper and the following paper in the conveyance path 118 e is expanded to be equal to or more than a reference interval provided in normal paper conveyance. In this way, it is possible to more simply and reliably prevent or reduce the reoccurrence of the jam in the automatic purge and to prevent jam processability from deteriorating.

FIG. 10 is an explanation diagram illustrating places of the papers remaining in the humidifying device of the image forming system when the jam has occurred in the post-processing device. FIG. 11 is an explanation diagram illustrating places of the papers withdrawn to places, other than the specific places, in the humidifying device before the conveyance of papers is temporarily stopped after the occurrence of the jam. In FIG. 10 and FIG. 11, the paper feeding device 120 is omitted in order to facilitate a description.

In FIG. 10, similarly to FIG. 7, the occurrence place of the jam is indicated by the mark X. The number of papers, other than the originating paper, remaining in the image forming system 100 when the jam has occurred is 4, wherein all the papers remain in the conveyance path 138 of the humidifying device 130.

In FIG. 11, among the papers P2 to P5 remaining in the humidifying device 130 at the time of the occurrence of the jam, the paper P4 remaining in the humidifying unit 136 which is the specific place, is conveyed for withdrawal from the humidifying unit 136 to a proper place, other than the specific place, at a downstream side from the humidifying unit 136. The reason for setting the humidifying unit 136 as the specific place is because when the paper is temporarily stopped in the humidifying unit 136 and when the paper is reconveyed from the humidifying unit 136, the paper may be broken or deformed by the humidifying roller. Furthermore, this is because when the paper stayed in the humidifying unit 136 is continuously humidified and thus is excessively humidified, the paper may be deformed, broken, or absorbed to the device, and at the time of paper reconveyance, paper conveyance failure may occur.

The paper P4 remaining in the specific place, for example, can be conveyed for withdrawal to the proper place, other than the specific place, at a downstream side from the humidifying unit 136 by rotationally driving the humidifying roller of the humidifying unit 136.

As described above, the paper P4 remaining in the humidifying unit 136 is withdrawn to the proper place, other than the specific place, and the automatic purge is performed from the place, other than the humidifying unit 136, so that it is possible to suppress conveyance failure of the paper remaining in the humidifying unit 136 in the automatic purge.

The papers P2 to P5 remaining in the humidifying device 130 are respectively conveyed under the control of the CPU 131 in the automatic purge in such a way that an interval between the preceding paper and the following paper in the conveyance path 118 e is expanded. In this way, it is possible to prevent or reduce the reoccurrence of the jam in the automatic purge and to prevent jam processability from deteriorating.

FIG. 12 is a flowchart illustrating processing from jam occurrence to automatic purge in the image forming system. The present flowchart can be executed by the CPU 111 of the image forming apparatus 110 according to the program stored in the storage unit 112 of the image forming apparatus 110.

The CPU 111 of the image forming apparatus 110 continues image formation on the paper until it is detected that the jam has occurred in the image forming system 100 (S121: NO, S126). The CPU 111 detects the jam having occurred in the image forming system 100 based on the positions of the papers detected by the paper sensor 1119. The CPU 111 detects the jam having occurred in the other devices of the image forming system 100 by receiving information of jam occurrence from the other devices. Each device, in which the jam has occurred, can detect the occurrence of the jam based on the positions of the papers detected by each of the paper sensors 139, 149, and 128.

When the CPU 111 detects that the jam has occurred in the image forming system 100 (S121: YES), the CPU 111 communicates with the other devices and temporarily stops the conveyance of the papers remaining in the image forming system 100 (S122).

Before stopping the conveyance of the papers in S122, the CPU 111 may withdraw the papers remaining in each device of the image forming system 100 to places other than the specific places.

When the CPU 111 determines that the originating paper of the jam has been removed based the positions of the papers detected by the paper sensor 1119 or the information received from the other devices (S123: YES), the CPU 111 determines whether automatic purge is possible (S124).

When it is determined that the automatic purge is not possible (S124: NO), the CPU 111 ends the procedure without performing the automatic purge. The case, in which it is determined that the automatic purge is not possible, for example, includes the case in which the papers remaining in the image forming system 100 are determined as continuous papers, and the case in which the remaining papers are not withdrawn and remain in the specific places.

When it is determined that the automatic purge is possible (S124: YES), the CPU 111 performs the automatic purge (S125).

FIG. 13 is a sub-routine flowchart of step S125 of the flowchart of FIG. 12.

The CPU 111 of the image forming apparatus 110 communicates with the other devices and detects the number Nmax of the papers, other than the originating paper, remaining in the image forming system 100 (S131). The number of the papers remaining in each device of the image forming system 100 can be detected based on the number of the papers detected by the paper sensors 1119, 139, 149, and 128 of each device.

In the example of the state of the papers after the conveyance stop illustrated in FIG. 9, since the number of the papers remaining in the image forming system 100 is 4 and the number of the papers remaining in the paper feeding device 120 is 2, the number Nmax of the papers, other than the originating paper, remaining in the image forming system 100 is 6.

In step S131, the discharge order of the remaining papers from the image forming system 100 is further decided. Hereinafter, a description will be provided for the case in which the paper with the discharge order N^(th) from the image forming system 100 is an N^(th) remaining paper.

The CPU 111 sets a counter value N of an internal counter to 1 (S132).

The CPU 111 starts the conveyance of the N^(th) remaining papers (S133).

When the CPU 111 determines that there is no following paper of the N^(th) remaining paper (S134: NO), the CPU 111 ends the automatic purge process after determining that the final remaining paper has been discharged from the image forming system 100 (S139). The counter value N of the internal counter reaches Nmax, so that it is determined that there is no following paper of the N^(th) remaining paper.

When there is the following paper of the N^(th) remaining paper (S134: YES), the CPU 111 determines whether it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper (S135).

FIG. 14 is a diagram illustrating a detailed flow of the determination in step S135 of the flowchart of FIG. 13.

When the CPU 111 of the image forming apparatus 110 determines that the N^(th) remaining paper does not remain in temporary stop positions provided in normal paper conveyance (S141: NO), the CPU 111 determines that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135 of FIG. 13. In the case in which the N^(th) remaining paper as the preceding paper does not remain in the temporary stop positions provided in the normal paper conveyance, when reconveyance is performed from the remaining position of the N^(th) remaining paper, it is relatively highly probable that the bending, the inclination, or the deviation of the paper occurs or deformation or breakage of the paper occurs.

The temporary stop positions provided in the normal paper conveyance, for example, correspond to the remaining positions of the papers P2, P3, P4, P6, and P7 in FIG. 8. In the conveyance path of the humidifying device 130, all positions correspond to positions other than the temporary stop positions provided in the normal paper conveyance.

When it is determined that the N^(th) remaining paper remains in the temporary stop positions provided in the normal paper conveyance (S141: YES), the CPU 111 determines whether the N^(th) remaining paper remains in the positions in which the bending, the inclination, and the deviation of the paper can be corrected (S142). The positions, in which the bending, the inclination, and the deviation of a paper can be corrected, for example, are upstream positions from the resist roller 118 a. That is, the position in which the resist roller 118 a exists in the conveyance path from remaining positions of the papers to discharge positions of the papers. For example, in FIG. 8, the remaining positions of the papers P2 to P7 correspond to the positions in which the bending, the inclination, and the deviation of the paper can be corrected. In the conveyance path of the humidifying device 130, all the positions correspond to positions in which the correction of the bending, the inclination, and the deviation of the paper is not possible.

When the CPU 111 determines that the N^(th) remaining paper does not remain in the positions in which the bending, the inclination, and the deviation of the paper can be corrected (S142: NO), the CPU 111 determines that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135. In the automatic purge, when the bending, the inclination, or the deviation of the paper may occur due to reconveyance and is not corrected, it is probable that paper conveyance failure occurs.

When it is determined that the N^(th) remaining paper remains in the positions in which the bending, the inclination, and the deviation of a paper can be corrected (S142: YES), the CPU 111 determines whether the paper interval between the N^(th) remaining paper and the following paper is smaller than the reference interval provided in the normal paper conveyance (S143).

When it is determined that the paper interval between the N^(th) remaining paper and the following paper is smaller than the reference interval (S143: YES), the CPU 111 determines that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135. This is because the paper interval between the preceding paper and the following paper is smaller than the reference interval, resulting in an increase in the probability that conveyance failure occurs due to a collision of the preceding paper and the following paper. On the other hand, when it is determined that the paper interval between the N^(th) remaining paper and the following paper is not smaller than the reference interval (S143: NO), the CPU 111 determines that it is not necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135. For example, in FIG. 8, the interval between the paper P2 and the paper P5 is smaller than the reference interval. This is due to withdrawing papers to the ADU which is a place other than the specific places. Furthermore, in FIG. 11, the interval between the paper P3 and the paper P4 is smaller than the reference interval. This is due to withdrawing the paper P4 to the downstream in order to prevent papers from staying in the humidifying unit 136 which is the specific place.

Returning to FIG. 13, when it is determined that it is not necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135 (S135: NO), the CPU 111 increments the counter value of the internal counter (S138) and returns to step S133 to continue the process on an N+1^(th) remaining paper.

When it is determined that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135 (S135: YES), the CPU 111 delays the start of conveyance of the following paper by a predetermined time from the start of the N^(th) remaining paper, thereby expanding the paper interval between the N^(th) remaining paper and the following paper in step S136 and step S137.

The predetermined time may differ in (1) when it is determined that the N^(th) remaining paper does not remain in the temporary stop positions provided in the normal paper conveyance (S141: NO), (2) when it is determined that the N^(th) remaining paper does not remain in the positions in which the bending, the inclination, and the deviation of the paper can be corrected (S142: NO), and (3) when it is determined that the paper interval between the N^(th) remaining paper and the following paper is smaller than the reference interval (S143: YES).

For example, in the case of (3), a time, in which the paper interval between the N^(th) remaining paper and the following paper becomes the reference interval, can be set as the predetermined time (a fourth time). In the case of (2), in consideration of the fact that the bending, the inclination, and the deviation of the N^(th) remaining paper are not corrected, the predetermined time can be set as a time (a third time) longer than the case of (3). In the case of (1), in consideration of the fact that the N^(th) remaining paper does not remain in the temporary stop positions provided in the normal paper conveyance, the predetermined time can be set as a time (a second time) longer than the case of (2).

In addition, even though it is not determined that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S135 (S135: NO), the paper interval between the N^(th) remaining paper and the following paper may also be expanded. In this case, the predetermined time may also be set as a fixed time (a first time) shorter than the cases of (1) to (3).

The CPU 111 stops the following paper (the N+1^(th) remaining paper) until the conveyance time of the N^(th) remaining paper reaches a timer value Tn provided for each N^(th) remaining paper, thereby expanding the paper interval between the N^(th) remaining paper and the following paper. In this case, delaying the start of conveyance of the following paper by the predetermined time from the start of the N^(th) remaining paper corresponds to expanding the paper interval between the N^(th) remaining paper and the following paper. Specifically, the timer value Tn is set for each N^(th) remaining paper by the degree by which the paper interval between the N^(th) remaining paper and the following paper is expanded.

The CPU 111 sets the timer value Tn for the N^(th) remaining paper and starts the measurement of the conveyance time T of the N^(th) remaining paper (S136). The CPU 111 may set the timer value Tn by reading the timer value Tn set in advance by the user in correspondence to the position and the like of the remaining paper and stored in the storage unit 112.

The CPU 111 continues the conveyance of the N^(th) remaining paper until the conveyance time T of the N^(th) remaining paper reaches the timer value Tn (S137). The measurement of the conveyance time T, for example, can be performed using a program processing time required for a loop until No is determined again in step S137 after No is determined in step S137.

When the conveyance time T of the N^(th) remaining paper reaches the timer value Tn (S137: YES), the CPU 111 increments the counter value N of the internal counter (S138) and starts the conveyance of the N+1^(th) remaining paper (S133).

In this way, the CPU 111 can convey the papers remaining in the image forming system 100 while properly expanding the interval between the preceding paper and the following paper in response to the remaining position of a preceding paper or the interval between the preceding paper and the following paper, discharge the papers from the image forming apparatus 110, and discharge the papers from the image forming system 100.

The present embodiment has the following effects.

In the automatic purge after the originating paper having caused jam is removed, papers, other than the originating paper, remaining in the paper conveyance path are conveyed and discharged in such a way that an interval between the preceding paper and the following paper is expanded. In this way, regardless of the places of remaining papers when conveyance has been stopped due to the occurrence of the jam, it is possible to prevent or reduce the reoccurrence of the jam in the automatic purge and to prevent jam processability from deteriorating.

Moreover, before paper conveyance is temporarily stopped after the jam is detected, the papers, other than the originating paper, are conveyed for withdrawal to places, other than predetermined specific places in the conveyance path. In this way, the automatic purge is performed from the places, other than the specific places, so that it is possible to suppress paper conveyance failure in the automatic purge and more effectively prevent or reduce the reoccurrence of jam in the automatic purge.

Moreover, the papers, other than the originating paper, remaining in a conveyance path are respectively conveyed in such a way that the interval between the preceding paper and the following paper in a conveyance path is expanded by delaying the start of conveyance of the following paper by the predetermined time from the start of conveyance of the preceding paper. In this way, it is possible to expand the interval between the preceding paper and the following paper more simply and accurately.

Moreover, the papers, other than the originating paper, remaining in the conveyance path are respectively conveyed in such away that the interval between the preceding paper and the following paper in the conveyance path is expanded to be equal to or more than the reference interval provided in the normal paper conveyance. In this way, it is possible to more effectively prevent or reduce the reoccurrence of the jam in the automatic purge, and suppress an increase in a time required for the automatic purge by properly expanding the interval between the preceding paper and the following paper.

When the preceding paper remains in the temporary stop positions of the papers set in the normal paper conveyance, the papers, other than the originating paper, remaining in the conveyance path are conveyed in such a way that the interval between the preceding paper and the following paper in the conveyance path is maintained or expanded by simultaneously performing the start of the conveyance of the following paper and the start of the conveyance of the preceding paper or delaying the start of the conveyance of the following paper by the first time from the start of the conveyance of the preceding paper, and when the preceding paper remains in positions other than the temporary stop positions, the papers are conveyed in such a way that the interval between the preceding paper and the following paper is expanded by delaying the start of the conveyance of the following paper by the second time longer than the first time from the start of the conveyance of the preceding paper. In this way, when the remaining position of the preceding paper is the position other than the temporary stop positions, the papers are conveyed while expanding the interval between the preceding paper and the following paper, so that it is possible to suppress conveyance failure due to reconveyance from the position other than the temporary stop positions, and to effectively prevent the reoccurrence of the jam in the automatic purge.

Moreover, the conveyance of the papers, other than the originating paper, remaining in the conveyance path are conveyed such a way that, the conveyance of the following paper and the conveyance of the preceding paper are simultaneously started when there is the correction unit for correcting the bending and the like of the paper in the conveyance path from the remaining position of the preceding paper to discharge positions of papers, and the interval between the preceding paper and the following paper is expanded by delaying the start of the conveyance of the following paper by the third time from the start of the conveyance of the preceding paper when there is no correction unit. In this way, the bending and the like of the paper which are occurrable in reconveyance in the automatic purge are corrected, so that it is possible to suppress the paper conveyance failure and to more effectively prevent the reoccurrence of the jam in the automatic purge.

Moreover, the conveyance of the papers, other than the originating paper, remaining in the conveyance path are conveyed such that the interval between the preceding paper and the following paper is expanded by delaying the start of the conveyance of the following paper by the fourth time from the start of the conveyance of the preceding paper when the interval between the remaining position of the preceding paper and the remaining position of the following paper in the conveyance path is narrower than the reference interval, and when the interval between the remaining position of the preceding paper and the remaining position of the following paper is equal to or wider than the reference interval, the conveyance of the following paper and the conveyance of the preceding paper are simultaneously started. In this way, the papers are conveyed while expanding the paper interval to be equal to or more than the reference interval in the automatic purge, so that it is possible to suppress the conveyance failure due to the collision of papers and to more effectively prevent the reoccurrence of the jam in the automatic purge.

Second Embodiment

The image forming system and the image forming apparatus according to a second embodiment of the present invention will be described. Differences between the present embodiment and the first embodiment is that in the present embodiment, even though the preceding paper and the following paper remain in positions of the conveyance path conveyed by a common conveyance driving source, the automatic purge is performed to convey the papers while expanding the interval between the preceding paper and the following paper. Since the present embodiment is common to the first embodiment in other points, a description thereof will be omitted or simplified.

FIG. 15 is an explanation diagram illustrating the places of the remaining papers in the state in which papers have been withdrawn to the places other than the specific places in the humidifying device before paper conveyance is temporarily stopped after the occurrence of the jam.

As illustrated in FIG. 15, the paper P3 and the paper P4 remain in the positions of the conveyance path 138 conveyed by a motor M1 which is a common conveyance driving source. Conveyance rollers R11, R12, R13, R14, and R15 are rotated by the motor M1 as the driving source. Conveyance rollers R21 and R22 are rotated by another motor M2 as the driving source.

The CPU 131 detects papers in each of the motor M1 and the motor M2, which exist in the positions of the conveyance path 138 conveyed by the motor M1 and the motor M2 respectively, based on the positions of the papers in the conveyance path 138, which have been detected by the paper sensor 139 constituting a first detection unit together with the CPU 131.

In the automatic purge, since the preceding paper P3 and the following paper P4 are conveyed by the common motor M1 as the conveyance driving source, it is not possible to convey only any one of the preceding paper P3 and the following paper P4, and it is not possible to expand the interval between the preceding paper P3 and the following paper P4.

In the present embodiment, when the remaining preceding paper P3 and following paper P4 remain in the positions of the conveyance path conveyed by the common motor M1, the conveyance of the preceding paper and the following paper is controlled as follows, so that the preceding paper and the following paper are conveyed while expanding the interval between the preceding paper and the following paper in the automatic purge.

FIG. 16 is an explanation diagram illustrating the state in which the automatic purge is performed from the state of FIG. 15 and the preceding paper has passed through the position of the conveyance path conveyed by the common conveyance driving source together with the following paper.

In the automatic purge, the CPU 131 simultaneously starts the conveyance of the preceding paper P3 and the following paper P4 by the motor M1 which is the common conveyance driving source (a first conveyance driving source). When the preceding paper P3 has passed through the position of the conveyance path conveyed by the common motor M1 together with the following paper P4 (that is, when the rear end of the preceding paper P3 has passed through the conveyance roller R15), the CPU 131 temporarily stops the motor M1 to stop the conveyance of the following paper P4, and continues the conveyance of the preceding paper P3 by the motor M2 which is another conveyance driving source (a second conveyance driving source). In this way, it is possible to convey the preceding paper P3 and the following paper P4 while expanding the interval between the preceding paper P3 and the following paper P4.

FIG. 17 is a flowchart of the automatic purge in the present embodiment and is a sub-routine flowchart of step S125 of the flowchart of FIG. 12.

The CPU 111 of the image forming apparatus 110 communicates with the other devices of the image forming system 100 and detects the number Nmax of the papers, other than the originating paper, remaining in the image forming system 100 (S1701).

The CPU 111 sets the counter value N of the internal counter to 1 (S1702).

The CPU 111 starts the conveyance of the N^(th) remaining papers (S1703).

When the CPU 111 determines that there is no following paper of the N^(th) remaining paper (S1704: NO), the CPU 111 ends the automatic purge process after determining that the final remaining paper has been discharged from the image forming system 100 (S1712).

When there is the following paper of the N^(th) remaining paper (S1704: YES), the CPU 111 determines whether it is necessary to expand the paper interval with the following paper (S1705).

When it is determined that it is not necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S1705 (S1705: NO), the CPU 111 increments the counter value of the internal counter (S1711) and returns to step S1703 to continue the process on an N+1^(th) remaining paper which is the following paper of the N^(th) remaining paper.

When it is determined that it is necessary to expand the paper interval between the N^(th) remaining paper and the following paper in step S1705 (S1705: YES), the CPU 111 determines whether the N^(th) remaining paper and the following paper (the N+1^(th) remaining paper) remain in the positions of the conveyance path conveyed by the common conveyance driving source (S1706).

When it is determined that the N^(th) remaining paper and the following paper do not remain in the positions of the conveyance path conveyed by the common conveyance driving source (S1706: NO), the CPU 111 sets the timer value Tn for the N^(th) remaining paper and starts the measurement of the conveyance time T of the N^(th) remaining paper (S1709).

The CPU 111 continues the conveyance of the N^(th) remaining paper until the conveyance time T of the N^(th) remaining paper reaches the timer value Tn (S1710), increments the counter value N of the internal counter (S1711), and starts the conveyance of the N+1^(th) remaining paper (S1703).

On the other hand, when it is determined that the N^(th) remaining paper and the following paper remain in the positions of the conveyance path conveyed by the common conveyance driving source (S1706: YES), the CPU 111 continues the conveyance of the N^(th) remaining paper (and the N+1^(th) remaining paper which is the following paper) until the N^(th) remaining paper passes through the position of the conveyance path conveyed by the common conveyance driving source (S1707).

When the N^(th) remaining paper has passed through the position of the conveyance path conveyed by the common conveyance driving source (S1707: YES), the CPU 111 temporarily stops of the conveyance of the N+1^(th) remaining paper which is the following paper (S1708), and continues the conveyance of the N^(th) remaining paper until the conveyance time T reaches the timer value Tn (a predetermined fifth time) (S1709 and S1710). Thereafter, the CPU 111 increments the counter value N of the internal counter (S1711), and starts the conveyance of the N+1^(th) remaining paper, which has been temporarily stopped (S1703).

The present embodiment has the following effects in addition to the effects of the first embodiment.

In the automatic purge from the state in which the preceding paper and the following paper, which are the papers remaining after the originating paper having caused jam is removed, remain in the positions of the conveyance path conveyed by the common conveyance driving source, the preceding paper and the following paper are conveyed by the common first conveyance driving source, the conveyance of the following paper by the first conveyance driving source is temporarily stopped when the preceding paper has passed through the position of the conveyance path conveyed by the first conveyance driving source, and continues the conveyance of the preceding paper by the other second conveyance driving source. In this way, even though the automatic purge is performed from the state in which the remaining preceding paper and following paper remain in the positions of the conveyance path conveyed by the common conveyance driving source, it is possible to convey the papers while expanding the interval between the preceding paper and the following paper, to prevent or reduce the reoccurrence of the jam in the automatic purge, and to prevent jam processability from deteriorating.

Third Embodiment

The image forming system and the image forming apparatus according to a third embodiment of the present invention will be described. Differences between the present embodiment and the first embodiment is that in the present embodiment, in the automatic purge, in the case of conveying the remaining papers, when it is detected that the conveyance of the preceding paper is started and the preceding paper has passed through predetermined positions of the conveyance path, the conveyance of the following paper is started, so that the preceding paper and the following paper are conveyed while expanding the interval between the preceding paper and the following paper. Since the present embodiment is common to the first embodiment in other points, a description thereof will be omitted or simplified.

Each of the paper sensors 1119, 139, 149, and 128 of the image forming system 100 constitutes a second detection unit together with each of the CPUs 111, 131, 141, and 121, and detects that the paper has passed through predetermined positions of the conveyance path. The fact that the paper has passed through the predetermined positions of the conveyance path can be detected by detecting the rear end of the paper has passed through each of the paper sensors 1119, 139, 149, and 128. The predetermined positions of the conveyance path, for example, may be the downstream ends of the conveyance paths 148 b and 148 d of the post-processing device 140, or the downstream end of the conveyance path 118 e of the image forming apparatus 110.

FIG. 18 is a flowchart of the automatic purge in the present embodiment and is a sub-routine flowchart of step S125 of the flowchart of FIG. 12.

The CPU 111 of the image forming apparatus 110 communicates with the other devices of the image forming system 100 and detects the number Nmax of the papers, other than the originating paper, remaining in the image forming system 100 (S181).

The CPU 111 sets the counter value N of the internal counter to 1 (S182).

The CPU 111 starts the conveyance of the N^(th) remaining paper (S183).

When the CPU 111 detects that the N^(th) remaining paper has been discharged from the image forming system 100 bypassing through the downstream ends which are the predetermined positions of the conveyance paths 148 b and 148 d of the post-processing device 140 (S184: YES), the CPU 111 determines whether there is the N+1^(th) remaining paper which is the following paper (S185), and ends the procedure when it is determined that there is no following paper (S185: NO).

When it is determined that there is the following paper (S185: YES), the CPU 111 increments the counter value N of the internal counter to 1 (S186) and starts the conveyance of the N+1^(th) remaining paper (S183).

The present embodiment has the following effects in addition to the effects of the first embodiment.

In the automatic purge performed after the originating paper having caused the jam is removed, when it is detected that the conveyance of the remaining preceding paper is started and the preceding paper has passed through the predetermined positions of the conveyance path, the conveyance of the following paper is started, so that the preceding paper and the following paper are conveyed while expanding the interval between the preceding paper and the following paper. In this way, the collision of the preceding paper and the following paper in the automatic purge is more reliably prevented, so that it is possible to more effectively prevent or reduce the reoccurrence of the jam in the automatic purge, and to prevent jam processability from deteriorating.

The image forming system and the image forming apparatus according to the present invention are not limited to the aforementioned embodiments.

For example, in the aforementioned embodiments, the automatic purge process is performed by the program. However, the whole or a part of the process performed by the program may be performed by hardware such as a circuit. 

What is claimed is:
 1. An image forming system comprising: a jam detection unit which detects a jam of a paper conveyed along a conveyance path of said image forming system; and a control unit which temporarily stops conveyance of the paper when said jam detection unit has detected said jam, after an originating paper having caused said jam is removed, conveys papers, other than said originating paper, remaining in said conveyance path in such a way that an interval between a preceding paper and a following paper in said conveyance path is expanded, and discharges said papers from said image forming system.
 2. The image forming system as claimed in claim 1, wherein, before temporarily stopping said conveyance of said paper after said jam detection unit detects said jam, said control unit withdraws said papers, other than said originating paper, by conveying said papers to a place other than a predetermined specific place in said conveyance path.
 3. The image forming system as claimed in claim 1, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying start of conveyance of said following paper by a predetermined time from start of conveyance of said preceding paper.
 4. The image forming system as claimed in claim 1, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded to be equal to or more than a reference interval provided in normal paper conveyance.
 5. The image forming system as claimed in claim 3, wherein, when said preceding paper remains in a temporary stop position of a paper set in normal paper conveyance, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is maintained or expanded by simultaneously performing said start of said conveyance of said following paper and said start of said conveyance of said preceding paper or delaying said start of said conveyance of said following paper by a first time as said predetermined time from said start of said conveyance of said preceding paper, and when said preceding paper remains in a position other than said temporary stop position, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a second time as said predetermined time longer than said first time from said start of said conveyance of said preceding paper.
 6. The image forming system as claimed in claim 3, further comprising: a correction unit which corrects at least one of bending, inclination, and deviation of the passing paper, wherein, when said correction unit exists in said conveyance path from a remaining position of said preceding paper to discharge positions of the papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said conveyance of said following paper and said conveyance of said preceding paper are simultaneously started, and when said correction unit does not exist in said conveyance path from said remaining position of said preceding paper to said discharge positions of said papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a third time as the predetermined time from said start of said conveyance of said preceding paper.
 7. The image forming system as claimed in claim 4, wherein, when the interval between the remaining position of said preceding paper and the remaining position of said following paper in said conveyance path is narrower than said reference interval, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a fourth time as the predetermined time from said start of said conveyance of said preceding paper, and when said interval between said remaining position of said preceding paper and said remaining position of said following paper is equal to or wider than said reference interval, said control unit simultaneously starts said conveyance of said following paper and said conveyance of said preceding paper.
 8. The image forming system as claimed in claim 1, further comprising: a first detection unit which detects a paper, which exists in at least a position of said conveyance path conveyed by each conveyance driving source, in said each conveyance driving source respectively, wherein, when said first detection unit detects that said preceding paper and said following paper remain in at least positions of said conveyance path conveyed by a common first conveyance driving source, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by conveying said preceding paper and said following paper until said preceding paper passes through at least said position of said conveyance path conveyed by said first conveyance driving source, temporarily stopping conveyance of said following paper by said first conveyance driving source and conveying said preceding paper by a second conveyance driving source other than said first conveyance driving source when said preceding paper has passed through at least said position of said conveyance path conveyed by said first conveyance driving source, and restarting said conveyance of said following paper by said first conveyance driving source after a predetermined fifth time passes, and discharges said papers from said image forming system.
 9. The image forming system as claimed in claim 1, further comprising: a second detection unit which detects that a paper has passed through a predetermined position in said conveyance path, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such away that said interval between said preceding paper and said following paper in said conveyance path is expanded by starting conveyance of said following paper when said second detection unit detects that said preceding paper has passed through said predetermined position of said conveyance path after conveyance of said preceding paper is started.
 10. An image forming apparatus comprising: a jam detection unit which detects a jam of a paper conveyed along a conveyance path of an image forming system including said image forming apparatus; and a control unit which temporarily stops conveyance of a paper when said jam detection unit has detected said jam, after an originating paper having caused said jam is removed, conveys papers, other than said originating paper, remaining in said conveyance path in such a way that an interval between a preceding paper and a following paper in said conveyance path is expanded, and discharges said papers.
 11. The image forming apparatus as claimed in claim 10, wherein, before temporarily stopping said conveyance of said paper after said jam detection unit detects said jam, said control unit withdraws said papers, other than said originating paper, by conveying said papers to a place other than a predetermined specific place in said conveyance path.
 12. The image forming apparatus as claimed in claim 10, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying start of conveyance of said following paper by a predetermined time from start of conveyance of said preceding paper.
 13. The image forming apparatus as claimed in claim 10, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded to be equal to or more than a reference interval provided in normal paper conveyance.
 14. The image forming apparatus as claimed in claim 12, wherein, when said preceding paper remains in a temporary stop position of a paper set in normal paper conveyance, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is maintained or expanded by simultaneously performing said start of said conveyance of said following paper and said start of said conveyance of said preceding paper or delaying said start of said conveyance of said following paper by a first time as said predetermined time from said start of said conveyance of said preceding paper, and when said preceding paper remains in a position other than said temporary stop position, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a second time as said predetermined time longer than said first time from said start of said conveyance of said preceding paper.
 15. The image forming apparatus as claimed in claim 12, further comprising: a correction unit which corrects at least one of bending, inclination, and deviation of the passing paper, wherein, when said correction unit exists in said conveyance path from a remaining position of said preceding paper to discharge positions of the papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said conveyance of said following paper and said conveyance of said preceding paper are simultaneously started, and when said correction unit does not exist in said conveyance path from said remaining position of said preceding paper to said discharge positions of said papers, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a third time as the predetermined time from said start of said conveyance of said preceding paper.
 16. The image forming apparatus as claimed in claim 13, wherein, when the interval between the remaining position of said preceding paper and the remaining position of said following paper in said conveyance path is narrower than said reference interval, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by delaying said start of said conveyance of said following paper by a fourth time as the predetermined time from said start of said conveyance of said preceding paper, and when said interval between said remaining position of said preceding paper and said remaining position of said following paper is equal to or wider than said reference interval, said control unit simultaneously starts said conveyance of said following paper and said conveyance of said preceding paper.
 17. The image forming apparatus as claimed in claim 10, further comprising: a first detection unit which detects the paper, which exists in at least a position of said conveyance path conveyed by each conveyance driving source, in said each conveyance driving source respectively, wherein, when said first detection unit detects that said preceding paper and said following paper remain in at least positions of said conveyance path conveyed by a common first conveyance driving source, said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such a way that said interval between said preceding paper and said following paper in said conveyance path is expanded by conveying said preceding paper and said following paper until said preceding paper passes through at least said position of said conveyance path conveyed by said first conveyance driving source, temporarily stopping conveyance of said following paper by said first conveyance driving source and conveying said preceding paper by a second conveyance driving source other than said first conveyance driving source when said preceding paper has passed through at least said position of said conveyance path conveyed by said first conveyance driving source, and restarting said conveyance of said following paper by said first conveyance driving source after a predetermined fifth time passes, and discharges said papers from said image forming system.
 18. The image forming apparatus as claimed in claim 10, further comprising: a second detection unit which detects that the paper has passed through a predetermined position in said conveyance path, wherein said control unit conveys said papers, other than said originating paper, remaining in said conveyance path in such away that said interval between said preceding paper and said following paper in said conveyance path is expanded by starting conveyance of said following paper when said second detection unit detects that said preceding paper has passed through said predetermined position of said conveyance path after conveyance of said preceding paper is started. 